138937021 has 2 divisors, whose sum is σ = 138937022. Its totient is φ = 138937020.

The previous prime is 138937013. The next prime is 138937049. The reversal of 138937021 is 120739831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 138909796 + 27225 = 11786^2 + 165^2 .

It is a cyclic number.

It is not a de Polignac number, because 138937021 - 2³ = 138937013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138937061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69468510 + 69468511.

It is an arithmetic number, because the mean of its divisors is an integer number (69468511).

Almost surely, 2^138937021 is an apocalyptic number.

It is an amenable number.

138937021 is a deficient number, since it is larger than the sum of its proper divisors (1).

138937021 is an equidigital number, since it uses as much as digits as its factorization.

138937021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 138937021 is about 11787.1549154153. The cubic root of 138937021 is about 517.9319004805.

The spelling of 138937021 in words is "one hundred thirty-eight million, nine hundred thirty-seven thousand, twenty-one".